The United Nations Children's Fund (UNICEF) said another 400 should be released over the next two days, UN deputy spokesperson Farhan Haq was quoted as saying by media.

The armed group, the South Sudan Democratic Army Cobra Faction, has advised UNICEF that they have up to 3,000 child soldiers, said Haq.

It is the third release of children following a peace deal between the armed group and the government, said Haq, adding that the UN Mission in South Sudan (UNMISS) has assisted with the screening and verification of the children who have been released.

Last year, 12,000 children, mostly boys, were recruited and used as soldiers by armed forces and groups in South Sudan as a whole, according to UNICEF.

The UN Security Council will hold an open debate on children and armed conflict on Wednesday. The debate is expected to focus on the issue of child victims of non-state armed groups, and the tools to exert pressure on these groups.